Phase-matched self-doubling optical parametric oscillator

Frequency conversion using synchronously pumped optical parametric oscillators (OPO) extend the wavelength range of ultrafast laser systems. Further wavelength extension can be obtained by frequency doubling one of the OPO beams with the use of another crystal inside the cavity. We report a self-doubling OPO where a single nonlinear crystal is employed for both parametric generation and frequency doubling. Our self-doubling OPO is based on a KTP (KTiOPO/sub 4/) crystal that is pumped by a Ti:sapphire laser operating at a wavelength of 739 nm.